SummaryIntensive care is one of the most costly areas of hospital care. Unfortunately, because of the diversity of case mix, costing intensive care is difficult. Many described costing methods previously are limited by being cumbersome, laborious to apply and expensive. The aim of this study was to develop a method for costing intensive care which can be applied with ease but facilitate meaningful cost comparisons between intensive care units. The method developed was based on cost blocks where the major components were identified and costed in a 'top-down' manner. Using strict definitions, the cost blocks attempted to measure the costs of equipment, estates, nonclinical support services (such as hospital management costs), clinical support services (such as physiotherapy, laboratory services), consumables (such as drugs, fluids and disposables) and staff. The study found that clinical support services, consumables and staff costs accounted for approximately 85% of the total costs.

These results demonstrate that TISS reliably measures overall ICU population costs as well as those of the subgroups CCU, CS and GIC. However, the relationship between TISS and cost is less reliable for the individual patient.

Background: Severe hyper- and hyponatraemia is associated with significant risks, yet its correction can also have serious consequences when implemented too fast or inadequately. The safe correction of serum sodium levels is particularly challenging when renal replacement therapy (RRT) is required. Methods: Using 2 case scenarios, we aim to illustrate a simple method of correcting hyper- and hyponatraemia safely by step-wise manipulation of the dialysate/replacement fluid. Results: During continuous RRT, hypernatraemia can be corrected effectively and safely by adding small pre-calculated amounts of 30% NaCl to the dialysate/replacement fluid bags aiming for a [Na⁺] in the fluid that allows safe equilibration and correction of the serum [Na⁺]. To correct hyponatraemia safely, pre-calculated amounts of sterile water can be added in a step-wise manner to achieve a fluid [Na⁺] that equals the desired target serum [Na⁺]. Conclusion: During continuous RRT, the step-wise adjustment of [Na⁺] of dialysate/replacement fluids offers a safe and reliable method to correct sodium disorders.

In patients with acute kidney injury and concomitant severe hyponatraemia or hypernatraemia, rapid correction of the serum Na+ concentration needs to be avoided. The present paper outlines the principles of how to adjust the Na+ concentration in the replacement fluid during continuous renal replacement therapy to prevent rapid changes of the serum Na+ concentration.